Two-dimensional displays



July 10, 1962 H. HURvlTz TWO-DIMENSIONAL DISPLAYS Filed April 27, 1955 4 mf/u. MF

United StatesPatentD 3,043,988 TWO-DIMENSIONAL DISPLAYS Hyman H urvitz, 737 'Warner Bldg.,'Washington, D.C. vFiled Apr. 27,1955, Ser. No. 504,329

16 Claims. (Cl. 315-169) The .present invention relates general-ly to two-dimen- Vsional displays, `and more particularly to two-dimensional displays produced by two groups of conductors, the -conductors of one .group .intersecting the conductors of the Aother group, and the intersecting points of conductor pairs Iselected `from the separate groups being provided with voltage sensitive material.

Briefly describing the present invention, I utilize (in a .preferred embodiment) `a irst group of conductors which are spaced Vone from the other and extend parallel Vto one another. I -further utilize a second group of conductors which are similarly spaced and similarly extend parallel to one another, the conductors of one group being located 4underneath the conductor-s -ofv the othergronp in spaced intersecting relation. In the space at the points of lintersection of the conductors, and located therebetween, is

provided a voltage sensitive material which `may -be speciically electroluminescent phosphor, yor voltage sensitive 'recording paper of the Atype commonly known as Teledeltos. Itis known that Teledeltos `paper provide no recording unless the vapplied voltage is greater than a predetermined value. Similarly, elec'troluminescent phos- `-phor .has the property that unless voltage of at least predetermined magnitude is applied, at any predetermined frequency, the phosphor will not glow substantially.

In .accordance with the .present invention signals are selectively applied to the conductors of one .group in accordance 'with the frequencies of the signals, and also to the conductors of the other group in accordance with further frequencies. The signals applied to theconductors are amplitude limited, to assure that any signal lapplied Ito any one conductor, in the absence of a further signal applied to an intersecting conductor, will produce no visual response. Since the process of amplitude limiting Vresults in the .generation of harmonics the outputs of V the .amplitnde limiters employed in the practice ofthe invention are .'liltered -to eliminate such harmonics. Upon the 4application to a pair of intersecting conductors of simultaneous AC. voltages, the sum of the voltages intermittently is sulticient to actuate the visual indicating substance or in aterial at the point of intersection, resulting in a visual display at the point of intersection.

The selection of conductors between the groups of con- -ductors may be accomplished by connecting in series with each conductor a crystal tuned .to a selected frequency. The separate .groups of crystals may be relatively Widely divergent with respect to frequency, V while Vthe crystals within a .group may be relatively close in frequency.

, The voltage variaion applied to any conductor .may b'e amplified by connecting that conductor acrossone element of a resonant circuit. Preferably, to r'accomplish this, each crystal may be connected in series with a tuning condenser and a tuning coil, the conductor being connected intermediate the condenser and tuning coil, so that the resonant voltage rise across the tuning coil wi-llbe imparted to the entire conductor.

By virtue of the fact that fthe .frequencies applied tothe .conductors of any one group are adjacent, it is feasible to utilize a single tuning coil for an entiregroup -of conductors, or, in the alternative, to utilize a single tuning 'c ondenser for an entire group of conductors, provided that in the rst case one tuning condenser. is connected in series with each conductor, and in the second case one .tuningcoil lis connected in series with each ofthe conductors.

Itis another object of my invention to lprovide a displayV in termsfof crossed `groups-'of conductors, which are selectively energizedby -connecting the Iseparate conductors in 4series with piezo-electric crystals tuned to different frequencies.

Still a further object of the present invention 'resides in the provision `of a -group of conductors which may be selected individually, or in any desired arrangement or combination, by applying suitably -selected frequencies to suitable piezo-electric elements in series with the separate conductors. Y i

Another object of the .present invention resides in the Yprovision of means for resonantly varying the voltage of an extended conductor by connecting the conductor in series betweena ituning condenser and `a tunjnginductance which are connected in senies with a source-of voltage, to which the combination `of condenser and inductance is` series resonant.

The above and still further objects, features, and Yad,- vantages of the present invention will become apparent upon consideration of the `following detailed disclosure, yespecially when 'taken in conjunction with the accompany- .ing drawings, wherein: FIGURE .l 'is a schematic circuit diagram lof ja circuit capable of exciting a voltage sensitive element upon the yapplication fof -two selected frequencies simultaneously;

sponsento the application -of preselected control frequencies;

FIGURE 3 is a modification ofthe system of FIGURE 2 which lmay be utilized when closely adjacent `frequencies are utilized to `excite the elements of the matrix;

:FIGURE 'Il is a View showing' the application of the present invention to electroluminescent material, the latter providing a visual `display upon the application of suitable vol-tages to selected conductors; and Y FIGURE V5 .isa modification of the system o f FIGURE which Y'.fI'eledeltos paper is substituted for the electroiluminescent material of FIGURE 4.

Reefrring now more particularly to FIGURE l1 -of the accompanying drawings, the reference numeral 1 denotes 4a piezoelectric crystal tuned to a frequency f1 while the reference numeral 2 denotes a piezo-electric crystal Atuned toa different frequency J2. The piezo-electric crystal 1 is :in series with a terminal 3- to which signal of various .frequencies lmay be applied, thesefrequencies including .the frequencyjp Similarly, the piezo-electric crystal `2 is connected in series with a'terrninal y4 to which may be :applied .various frequencies including Ythe frequency-f2. The crystal .-1 is further connected in series with a tuning L.condenser 5 anda tuning Vcoil l'6, the combination of condenser -5 and inductance 6. being resonant to the 'same frequency `as is the crystall..4 Similarly, the crystal 2 is conf nected in .series with a tuning condenser 7 and an iniductance coil 8, the flatter two elements being resonant to the same frequency as the crystal v2. The electrolumi- .nescentphosphorcondenser 9 is connected across the coils l6 and 8.

. lUpon the application `of frequency .f1 to `terminal 3 .and o f frequency ,f2 to terminal 4, Acurrent ows through the crystals `1 and 2, Vand excites Vthe resonant circuits 5 by the Q factors of the coils 6 and 8. The electroluminescent phosphor -`9 is selected to havea minimum terminals 3 and 4 are so selected, that upon vthe application of only one of the frequencies f1, f2 the voltage vwith respect to ground which exists across the electroluminescent condenser 9 is less than tiring voltage. Upon the application of voltages to both terminals 3 and 4, the sum of the two voltages periodically exceeds that required to lire the phosphor condenser 9, and accordingly a glow is produced. It follows that on the application of one only of frequencies f1, f2 to the system, noglow appears at the electroluminescent condenser 9, while in the presence of frequencies f1 and f2 simultaneously such a glow does appear. j It will be apparent that in substiturtion of the velectroluminescent phosphor 9 may be utilized voltage sensitive recording paper (Teledeltos), or other voltage sensitive material.

Reference is now made to FIGURE 2 of the accompanying drawings, wherein is-shown a two-dimensional display device utilizing the principles established in FIG- URE 1 of the accompanying drawings. In FIGURE 2 the reference numeral 10 denotes an amplitude limiter,

which limits to apreselected value the amplitudes of signals applied to a terminal 11. Similarly, the amplitude `limiter -12 limits the amplitude of signals applied to a terminaly 13. It is well known that the outputs of amplitude limiters contain signals of frequencies harmonically related to those at the inputs. Accordingly, the output of the amplitude limiter 10 is filtered by lter 14 and the output of the amplitude limiter 12 by the filter 15,

'it beingthe function of the lters 14 and 1S to remove harmonic responses which were generated by the amplitude limiters 10 and 12. This is normally readily feasible, provided the band of frequencies applied to the 'terminals 11 and v13, respectively, are not unduly broad.

As the description proceeds it will become evident that it is not required in the present system to utilize wide bands of frequencies.

Assuming now that the outputs of the filters 14, 15

contain only sinusoidal waves, within vafpredetermined band of frequencies, and that these waves are all of the Such phosphors are well knownr and have been 4 is in excess of that applied at kthe terminal 16 by virtue ofthe resonant rise across the tuning coil 32. This resonant rise may be of the order of thirty or more times, depending upon the value of VQ of the coil 32.

Located adjacent to the elongated conductor 31 are further conductors 32, 33, 34, 35, 36 which are separated from the conductor 31, so as to be insulated therefrom and which extend parallel thereto. A similar group of conductors 37-,to 42, inclusive, extend at right angles to the conductors 31 to 36, and are separated with respect to one another by about the same spacing `as are the adjacent conductors 31 to v36, respectively. The various conductors are individually connected just as is the conductor 31, being provided each with a tuning coil and a tuning condenser, and accordingly the arrangement and connections of the individual conductors are not further described herein.

The groups of conductors 31 to 36 and 37 to 42 extend in mutually perpendicular directions, although other relative angles may be selected, and if desired one of the groups may extend circumferentially while the other group extends radially. In any event, points of intersection occur between individual conductors of the two separate groups. At the points of intersection the conductors are slightly separated, and in the Vspace between the conductor pairs is inserted electroluminescent material, as 44, or voltage sensitive recording paper, as 4S, of

' the type commonly sold commercially under` the trade name Teledeltos. The electroluminescent material and the Teledeltos paper are merely examples of voltage sensitive materials which have minimum thresholds below which applied voltage will not cause a visual response,

'minimum thresholds.

The lamplitude lvalues provide at the terminals 16 and 17 are such, and the Q values of the resonant circuits em- Y ployed are such, the term resonant circuits referring to same amplitude, the output of the filter 14 is applied to :Y

a terminal 176 and the output of the filter 15 to a terminal 17. The terminal 15 vis connected in series with aV plurality of piezo-electric crystals 18 to 23, inclusive, all in parallel. A terminal 17 likewise provides signal in parallel to a plurality of piezo-electric crystals 24 to 29 inclusive. 'Ihe crystals 18 to 23 are separated relatively narrowly in frequency, and are responsive individually to fre- .quencies provided at the terminal 16. Likewise vthe crystals 24 to 29 are individually slightly separated from one another in frequency, but all fall, in respect to reso- Y nant frequency, `within'the band of frequencies applied to terminal 17. Selectivity curves of crystals of adjacent frequency may overlap slightly if desired (or at 3 db downpoints of the curves), or may be Vso separated that 'substantially no overlap occurs.V The system will be c operative in either event.

Considering the crystal 18 as typical, it is connected in series with a tuning condenser 30, an elongated conductor 31 and a tuning coil 32, the latter proceeding to` ground or other reference point. The condenser 30 and the tuning coil 32 form a `series resonant circuit, which is `resonant to the same frequency as the piezo-electric 4crystal 18. Accordingly, the voltage across the tuning coil 32, or the voltage across the conductor 31, with respect to ground, varies in amplitude at the frequency which the crystal 18 passes, but the amplitude variation 'ductors.

combination of condenser and tuning coils such as 30, 32, for example, that application of voltage `to an element of one group of conductors in the absence of voltage applied to'an intersecting conductor does not cause a visual 1 display. Only upon the application of simultaneous vvoltages to two intersecting conductors does a visual display occur at the point of intersectionvof the con- Accordingly, a visual display point may be caused to occur at lany point in two dimensions, by selecting the frequencies applied to the terminals 16 and 17 so as to'cause simultaneous current flow through one crystal of the set 118 to 23 inclusive and one crystal of It will be apparent that any number of piezo-electric'crystals from the separate groups of crystals may be simultaneously excited by applying a group of frequencies to the terminals 16 and 17. Accordingly, lall the intersection points of the two-dimensional display may be caused to provide visual responses simultaneously, or any one or combination of intersection points may be energized.

The system of FIGURE 3 is generally similar to that of FIGURE 2, except in that a single inductance coil 50 is employed in conjunction with one group of conductors 31 to 36, and avsingle tuning coil 51 in conjunction with the intersecting group of conductors 37 to 42, respectively. This procedure is rendered possible if the piezo-electric elements 18 to 23 are sufficiently close in frequency, and similarly if the piezo-electric elements 24 to 29 are suflciently close in frequency. In practice this will usually be found to be the case.

While I have shown a condenser 30 in series with a 'tuning coil 50, it will be apparent to those skilled in the `in series with each of the conductors 31 `to 36, and a single tuning condenser be connected jointly to all conductors to ground, in place of the alternative arrangement. Similarly, in connection with conductors 37 to 42 a single condenser may the employed in substitution of coil 51, prov-ided a plurality o f tuning coils are employed in place of associated series condenser.

While I have described and illustrated one speciiic example of the present invention, it Will be clear that variations of the specific details of construction may be resorted to without departing from the true spirit of the invention as dened in the appended claims.

What I claim is:

1. A device for providing two-dimensional displays, comprising `at least one elongated conductive element, at least another elongated conductive element, said elongated elements positioned to intersect each other, voltage sensitive material located intermediate said elongated elements at their intersection, a piezo-electric crystal tuned to one frequency connected (in series with one of said elements, a piezoelectric crystal tuned to another frequency connected in series with the other of said elements, a separate tuning series condenser and tuning coil pair connected in series with each of said elements, each condenser `and tuning coil pair resonant to the frequency of one of said piezo-electric crystals.

2. In a. two-dimensional display, a first plurality of Vseparated conductors extending in a rst coord-inate, a

second plurality of separated conductors extending in a second coordinate, and all intersecting said rst plurality of separated conductors to form cross-over points, voltage sensitive visualizing material` located `at least intermediate the cross-over points of said conductors, ja piezoelectric crystal connected in series with each of said conductors, each of said crystals tuned to a different frequency, and means for applying signals to said crystals vat amplitudes such that only concurrent application of voltage to two conductors at a cross-over point thereof will eiect visualizing response of said voltage sensitive visualizing material, said voltage sensitive visualizing material having a response threshold in response to applied voltage below which no substantial response occurs.

3. The combination in accordance with claim 2, 'wherein is provided means for causing the voltage of each o f said conductors to vary resonantly with respect to a reference value, said last means including means for including each of said conductors across one element of a resonant circuit.

4. A device-for providing two-dimensional displays, comprising at least one elongated conductive element, at least another elongated conductive element, said elongated elements positioned to intersect each other, voltage sensitive material located intermediate said elongated elements at their intersection, a pass iilter tuned to one frequency connected in series with one of said elements, a pass lter tuned to another frequency connected in series with the other of said elements, a separate tuning series condenser and tuning coil pair connected in series With each of said elements, each condenser and tuning coil pair resonant to the frequency of one of said pass filters.

5. In a two-dimensional display, ka rst plurality of separated conductors extending in a -first coordinate, a second plurality of separated conductors extending in a second coordinate, and all intersecting said first plurality of separated conductors to `forni cross-over points, voltage sensitive visualizing material located at least intermediate the cross-over points of said conductors, a series resonant lter connected in series with each of said conductors, each of said filters tuned to a different frequency, and means for applying signals to said lters at amplitudes such that only concurrent application of voltage to two conductors at a cross-over point thereof will effect visualizing response of said voltage sensitive visualizing ma- 6 terial, said voltage rsensitive visualizing material having a response threshold in response to applied voltage rbelow which no substantial response occurs.

6. The combination in accordance with claim 5, wherelin is provided means lfor causing the voltage of each of said conductors `to vary resonantly with respect to a ref,- erencey value, said last means including means for including each of said conductors across one element of a resonant circuit.

"7. in a system for generating a visual display in response to two frequencies simultaneously, an electro-sensitive visual display device having two electrodes, said device having a predetermined minimum voltage for which a display is generated, a iirst series resonant circuit tuned to one of said ltwo frequencies, a Vsecond series resonant circuit tuned to the other of said two frequencies, each of said series resonant circuits including a Ytuning inductance and a tuning capacitor, and means connecting said electrodes to the junction of said tuning inductances and capacitors.

8. In a system for generating a visual indication in response only to signals at predetermined frequencies, an electro-sensitive display device having two electrodes, between which subsists electro-sensitive material, means comprising a iirst lter tuned to one of said frequencies for applying alternating voltage with respect to a point of reference potential to one of said electrodes, and means comprising a second filter tuned to the other of said frequencies for applying an alternating voltage with respect to said point of reference potential to the other of said electrodes.

9. In a system for generating a visual indication in an electro-sensitive medium, a pair of electrodes between which said electro-sensitive medium subsists, a terminal, a circuit having reactance of one sign connected between one electrode of said pair and said terminal, a circuit having reactance of one sign connected between( the other electrode of said pair and said terminal, and means resonating With each of said circuits so associated with said circuits that resonant rises in voltage occur at said terminals.

10. A system for generating a variation of condition in an electro-sensitive device, said device having terminals, in response only to simultaneous occurrence of a predetermined p-air of frequencies, comprising means for f effecting a resonant rise in voltage yfor one of said terminals in response to one of said frequencies, and means for eifecting a resonant rise in Voltage in the other of said terminals in response to the other of said frequencies.

1l. In a system for generati-ng `a visual display in response to two frequencies simultaneously, an electrosensitive visual display device having two electrodes, said device having a predetermined minimum voltage for which a display is generated, a -rst series resonant circuit tuned to one of said twofrequencies, a second circuit, said resonant circuit including an inductance and a capacitance, means connecting one of said electrodes to the junction of said inductance and capacitance, means connecting' the other of`said electrodes to a terminal of said second circuit, means for supplying signal `to said resonant circuit at the resonant frequency of said resonant circuit, and means for applying A.C. signal to said second circuit, the sum of the amplitudes of said signals being selected to equal at least said predetermined minimum voltage, and said signals individually having less than said predetermined minimum voltage.

l2. A system for applying signal selectively to the electrodes of a voltage sensitive indicator, comprising a series resonant circuit including an inductance and a capacitance, and means connecting said voltage sensitive indi- ,catlor across one of said inductance and said capacitance on y.

13. An electronic circuit for the excitation of a series `of electroluminescent elements comprising an electronic control circuit adapted to receive a burst of energy, said acariens` rality of driver circuits, and a resonant circuit operatively `:associated with each of said driver circuits, said resonantv circuits each including an electrolurninescent element.

14. An electronic circuit for the excitation of plu--v rality of electrolurninescent elements comprising an input circuit adapted to receive wave energy, a plurality of further circuits coupled in parallel to said input circuit, anda resonant circuit associated with each' of said further circuits, said resonant circuits each including at least one electroluminescent element. Y

15. The combination according to claim 14, wherein each of said resonant circuits is tuned to respond to a different frequencygcomponent of said Wave energy.

16. The combination according to claim 15, wherein 15 each ofsaid further circuits includes a resonant circuit.

References Cited in the file of this patent UNITED STATES PATENTS Parker et al July 5, 1921 Wald Apr. 15, 1930 Gardner Mar. 27, 1934 La Pierre Oct. 17, 1939 Rust June 18, 1940 Murphy v Feb. 29, 1944 Styren Feb. 20, 1951 Taylor Mar. 16, 1954 Piper Ian. 4, 1955 

